Between the Blaster worm and the Sobig virus, it's been a long two weeks for Windows users. But nobody with a Mac or a Linux PC has had to lose a moment of sleep over these outbreaks — just like in earlier “malware” epidemics.
This is not a coincidence.
The usual theory has been that Windows gets all the attacks because almost everybody uses it. But millions of people do use Mac OS X and Linux, a sufficiently big market for plenty of legitimate software developers — so why do the authors of viruses and worms rarely take aim at either system?
Even if that changed, Windows would still be an easier target. In its default setup, Windows XP on the Internet amounts to a car parked in a bad part of town, with the doors unlocked, the key in the ignition and a Post-It note on the dashboard saying, “Please don't steal this.”
Not opening strange e-mail attachments helps to keep Windows secure (not to mention it's plain common sense), but it isn't enough.
The vulnerabilities built in: Security starts with closing doors that don't need to be open. On a PC, these doors are called “ports” — channels to the Internet reserved for specific tasks, such as publishing a Web page.
These ports are what network worms like Blaster crawl in through, exploiting bugs in an operating system to implant themselves. (Viruses can't move on their own and need other mechanisms, such as e-mail or floppy disks, to spread.) It's canonical among security experts that unneeded ports should be closed.
Windows XP Home Edition, however, ships with five ports open, behind which run “services” that serve no purpose except on a computer network.
“Messenger Service,” for instance, is designed to listen for alerts sent out by a network's owner, but on a home computer all it does is receive ads broadcast by spammers. The “Remote Procedure Call” feature exploited by Blaster is, to quote a Microsoft advisory, “not intended to be used in hostile environments such as the Internet.”
Jeff Jones, Microsoft's senior director for “trustworthy computing,” said the company was heeding user requests when XP was designed: “What customers were demanding was network compatibility, application compatibility.”
But they weren't asking for easily cracked PCs either. Now, Jones said, Microsoft believes it's better to leave ports shut until users open the ones they need. But any change to this dangerous default configuration will only come in some future update.
In comparison, Mac OS X ships with zero ports open to the Internet.
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Windows XP, by default, provides unrestricted, “administrator” access to a computer. This sounds like a good thing but is not, because any program, worms and viruses included, also has unrestricted access.
Yet administrator mode is the only realistic choice: XP Home's “limited account,” the only other option, doesn't even let you adjust a PC's clock.
Mac OS X and Linux get this right: Users get broad rights, but critical system tasks require entering a password. If, for instance, a virus wants to install a “backdoor” for further intrusions, you'll have to authorize it. This fail-safe isn't immune to user gullibility and still allows the total loss or theft of your data, but it beats Windows' anything-goes approach. [Privacy Digest]